Modes Taken from the Medieval Epoch

On the past couple of months, we've been presenting you some articles about the sonorities that have been frequently
used on the 20th Century music, specifically in the scale area. As our last article on this series, we will
show you the modes.

We should not take the modes as a modern invention, but as an adaptation of the medieval modes that were used on the
Medieval and Renaissance Period. These Medieval modes consist of 8 modes: 4 authentic modes and 4 plagal modes (see
example no.1). All the authentic modes are odd numbers while the plagal modes are even numbers. This is so because each
one of the plagal modes was directly related to one authentic mode. Plagal modes contains the same pitches, except that
this mode started an interval 4th lower than its correspondent authentic mode.

Some theorists use Greek names such as Dorian, Phrygian, Lydian, and Mixo-Lydian to refer to the authentic modes I,
III, V, and VII respectively. As for plagal modes, the prefix hypo is added to the name of its authentic
relative: mode II becomes the Hypo-Doric mode, mode IV the Hypo-Phrygian one, etc.